Color photography



Filed Jan. 9, 1932 Patented Septflf'- V1932 I UNITED` ,STATES PATENT OFFICE GmBGE vSYDNEY WHITFIELD, OF"INGBAVE, ENGLAND, AASSIGNOB T ILFOBD LIIITE',

0F 111031), ENGLAND, A BRITISH COMPANY COLOR PHOTOGRAPHY Application led January 9, 1932, Serial No. 585,768, and in G reat Britain December 16, 1980.

.The term part-image as used herein, sig- Y es an image ofthe subject obtained lby means of lightcorresponding to a portion only of the spectrum. Generally three part images-are'made` ofthe Subject, viz, a blue, a

green and a red part-image.

The final photograph is prepared from these part-image-records in the form of nega'- tives, by making a colored positive print from each of them and combining these positives according to one or other of the known methods employing either the additive or -subtractive principle of color synthesis.

It is clearly desirable to expose simultaneously the sensitive sur-faces which are to record the part-images. It is also very desirable, in order to obtain geometrically similar images of identical size that the sensltive surfaces should be so placed as to occupy during exposure similar positions with regard to the subject to be photographed.

The present invention is' concerned with methods for the production of colored photographs of the type ,in which a single part-v image of the subject is. recorded on one sensit1ve emulslon, and s1multaneously two or more further" part-images of the subject are recorded through a multi-color screen on a second sensitive emulsion. d

The present invention provides for use in the production of colored photographs by methods ofthe above type, the combinationV Oia-transparent support, an emulsion layer which is adapted to record light from one "im region of the spectrum and is associated with that surface of the support which will face the lens, a second emulsionlayer whichis adapted to record light from at least two other spectral regions and is'associated with 5 the rear surface of the support, and sandwiched between the two emulsion layers and on the support a multi-color screen adapted to pass light corresponding to the spectral regions to be recorded by the rear emulsion 5 layer.kv f

Accordin to a feature ofthe invention the front emulslon, that is the one facing the lens,

is adapted to record light corresponding to; l

the blue region of the spectrumfonly, the rear emulsion is a panchromatic one so that light as from the green and red regions maybe recorded thereon-1and the multi-color screen which is sandwiched between the two emulsion layers -is a two-color screen comprising juxtaposed green and red elements.4 The la' screenmay be of either the linear, the mosaic or the random type, but the linear type is preferred.

When a single support is employed for the two emulsions the front emulsion layer may be a stripping layer, which is removed from thel sup ort after development, in order to ensure tllat the two emulsion layers are submitted to identical development conditions, and thus `to ensure that any shrinkage or 7. other distortion of the support due to the treatment in theI developing baths willatlect the two emulsion layers equally. i

Owing, however, to the diculty of manipulatin the emulsion layer during the opera: 75 tion o transference to a fresh support it'is preferred according to angther feature of the mvention to employ a compsite support comprising two separable layers (with or without an interposed layer of adhesive), each 30 carrying one of the emulsions.

-After development positives correspondingv l therefrom either through filters correspondmg in color respectively to the colors of the elements constituting the screen or by other known methods of image separation. Thus in the case of a two-color red and green screen,

two positives may be printed from the rear 9o emulsion, one through a red filter .and the other through a green filter. A third positive is printed from the negative obtained on the front emulsion layer." f

- A practical embodiment. of. the invention t will now be described by way of example, reference being made lto the acompanyingl drawing in which the single igure -is a diagrammatic illustration of the lm assembly r and lens.`

.camera with the blue-sensitiveemulsion 11 on the support 10 facing the lens 16, the other support 13 being arranged behind the firstmentioned film with the emulsion side 15 thereof away from the lens.

The films in this position are exposed to light in the camera, a correcting filter 18 beingpreferably associated, with the lenstointercept ultraviolet radiation and equalize the effects of the color components on the emulsion and thusto enable equally exposed partimages to be obtained.

In this manner the blue part-image is\ recorded on the front film and the red and green part-images on the rear film. The two films' are then developed, fixed, washed and Y. dried, care being taken to ensure equal treat- [ment of the films.

A positive is then printed from the blue part-image upon a suitably sensitized surface and two further positives are printed Ain a similar manner from the other iilm with its l associated two-color screen through green and red filters respectively onto suitably sensitized surfaces. v

Y These three positives may then be suitably.

inal picture or alternativelv the final picture may be prepared trans erring dyes from these positive part-images on to a single surface by imbibition in known manner. Again separategcopies of the red and green part negatives may be prepared for use in any other well-known manner.

It is to be understood that the method accordng to the invention may be arranged to give a four colored picture by substituting athree-color screen for the two-color screen referred to above.

I claim t 1. For use in the production of colored photographs the combination -of a transparent supporting-means, an emulsion adapted to record light from the blue` region of the spectrum carrled on that surface of the supporting means which will face the lens, a.

multi-color screen which is adapted to pass light corresponding to at yleast two other spectral regions and is carried on the rear surface of the supporting means, and an emulsion which'is superimposed on the multicolored screen and is adapted to record light passed by the screen.

2. For use in the roduction of colored photographs, the com ination of a transparent su porting means, an emulsion layer which 1s adapted to record light from the -blue region of the spectrum only and is carried impose by that surface of the supporting means which will face the lens, a second emulsion layer which is adapted to record light from at least two other spectral regions and is carried by the rear surface of the supporting means, and sandwiched between the two emulsion layers and carried by the supporting means a multi-color screen adapted to pass light corresponding to the spectral re- 1gions to be recorded by the rear .emulsion ayer. $3. For the production of-threecoler hotographs by the simultaneous exposure o two d sensitized surfaces placed one behind the other with respect .to the camera lens, the

ycombination of a transparent supporting means,l aI blue-sensitive emulsion carried on that surface of the supporting means which will face the lens, a panchromatic emulsion carried on the rear surface of the supporting means, and sandwichedbetween the two emulsion layers and carried on the supporting means a` two-color screencomprsing,

juxtaposed red and green elements. l

4. For -use in the productionf of colored photographs by the simultaneous exposure of two sensitized surfaces placed one behind the other with respect to the camera lens, the combination of a composite transparent support comprising a 'front layer and a back layer\which are superimposed but separable) from one another, a blue sensitive emulsion 1 carried on the outermostsurface of the front dyed and superimposed in register to give the on the outermost surface of the rear los transparent support, an 'emulsion which is I adapted to record light from the blue region of the spectrum and is carried by that surface of the'support which will face the lens in such manner that it can be readily stripped from the support after development, a multicolor screen which is adapted to pass light corresponding to at least two other s ectral regions and is carried by the rear sur ace of the sup ort, and an emulsion which is superon the multi-colored screen and is adapted to record light passed by the screen.

6. For the production of colored photographs by the simultaneous exposure of two sensitized surfaces placed one behind theL other with respect to the camera lens, the combination of a single transparent support,

an emulsion layer which is adapted to record light from the blue region of the spectrum, is carried by that surface of the support which will face the lens, and is adapted to be stripped from the support after development, a second emulsion layer which is adapted to record light from at least two other spectral regions and is carried by the rear surface of the support, and sandwiched between the two emulslon layers and on the support amulticolor screen adapted to pass light corres nding to the spectral regions to .be recor ed by the rear emulsion layer.

7. For use in the production of colored photographs, the combination withl an emulsion adapted to record light from the blue region of the spectrum and to face the lens,-

of a multicolor screen which is adapted to pass light-corresponding to at least two other spectral regions located at the rear of the said emulsion, an emulsion located at the rear of,\

said screen and adapted to record light passed by the screen, and means for supporting said emulsions and screen. v

In testimony whereof I aix my si ature. GEORGE SYDNEY WHITFI LD. 

